Process of making fire proofed wood and like cellular products



Patented May 12, 1931 PATENT OFFICE RALPH H. MGKEE, OF JERSEY CITY, NEWJERSEY PROCESS OF MAKING FIRE PROOFED WOOD AND'LIKE CELLULAR PRODUCTS1T0 Drawing.

This invention relates to a' rocess of making fire-proofed wood and 11 ecellular I fplroducts, and particularly to a process of re-proofing woodfurniture. An important object of the invention is to provide a processof the character referred to which is simple, eflicient and relativelyinexpensive.

Another object of the invention is to provide a process by which woodand "other like cellular products can be satisfactorily fire-proofed atordinary atmospheric pressure.

A further object of the invention is to 15 rovide an improved process ofproducing re-proofed articles of wood or other cellular material inwhich the article is first made in the desired form, and the articlesubsequently treated to fire-proof it.

A further object of the invention is to provide a process of thecharacter referred to which eliminates the necessity for constantlyresharpening the tools used in producing the article, such as isnecessary when the material which is used to form the article is firstfire-proofed and subsequently formed into the desired article.

A further object of the invention is to provide a process of thecharacter referred to which materially decreases the amount of dustwhich is usually incident to the production of fire-proofed wood andthe' like cellular products by processes in which the material used toform the article of furniture is fire-proofed prior to forming thearticle.

Other objects and advantages of the invention will become apparent fromthe following description.

Heretofore it has been proposed to fireroof wood furniture by coverinthe suraces thereof with a paint containing an incom'bustible materialsuch as silicate of soda, chalk and the like. It will be apparent thatthis method can not be used if it is desired that the grain of the woodbe visible in the finished product. It also is known that wood may befire-proofed by impregnating it under pressure with materials such asam- 9 monium sulfate, borax, ammonium phosof work on untreated wood.

Applicationfiled January 9, 1928. Serial No. 245,629.

phate, sodium phosphate and other similar products which when subjectedto temperature high enough to fuse the impregnating material, evolvenoncumbustible vapors, and leave fusible salts deposited in the pores ofthe wood. The impregnation of the material desired to be fire-proofedwith a fusible salt under pressure accordingly is the process mostcommonly used. This method has several disadvantages among which is thelength of time required to carry out the. process. After the wood hasbeen impregnated with the fire-proofing material it is necessary to dryit in. a kiln or similar drying device. The total time usually requiredfrom the time the wood is sent to the impregnating plant until it isreturned from the kiln, dried and ready for use by the furniture makeris ordinarily about six weeks. Another disadvantage of this process isthat the wood which has been impregnated with the salt is very dustywhen being worked .and is consequently objected to b the workman.Furthermore, sawing, p aning and otherwise working the impregnated woodis g accomplished with such diflicult that the tools used become dullvery rapidi y and it is necessary to resharpen them about three times asoften as would be required if the tools were used to perform an e ualamount awe of the rotary type, such as disk saws and band saws, heat upmuch more rapidly than they do when employed on untreated-wood and thereis a pronounced tendency for these tools to lose their temper. Textilessuch as curtains and portieres have been fire-proofed by treating themwith various salts such as ammonium phosphate, ammonium sulfate, borax,alum and other 99 salts, but this treatment has not proved successful inthe treatment of wood and like cellular products unless the impregnationhas been carried on under elevated pressure.

The most advantageous method of making fire-proofed furniture is by aprocess in which the furniture is first made up into the desiredfinished form from untreated mate-v rial and the article thereaftersubjected to a fireproofing treatment which may be 01 100 wood and thusfails as a medium for fireproofing the article.

I have discovered that I may successfully employ a solution of afire-proofing salt such for example, as an alkali metal phosphate, andpreferably a solution of ordinary ammonium phosphate (NHQ HPO in thepresence of a gaseous or readily volatile alkaline agent, such forexample as. ammonia or a gaseous or freely volatile alkyl derivativethereof but preferably ammonia, as a treating solution to render thearticle fire-proof. Amines have an even more marked basic character thanammonia and the lower amines are either gaseous or highly volatile.While these lower amines are well suited for use as agents for causingthe fire-proofing salt to penetrate the wood at ordinary atmosphericpressure and are removed by simply drying, their disagreeable odorrenders their use unpleasant. Of all the impregnation promotersinvestigated, ammonia has been found to be most satisfactory forpractical use. The formed article of furniture may be dipped in a bathof a solution of the character referred to, or the solution may besponged or sprayed on to the wood either at ordinary room temperature orpreferably at a temperature 10 or 20 F. above room temperature, or thearticle may be treated with the solution by any other desired method.The fire-proofing salt in the presence of the alkali rapidly penetratesthe fibers of the wood, and after allowing the article to dry for a fewdays by exposing it to the atmosphere, the free ammonia volatilizesleaving the fireproofing salt in tlie fibers of the wood so that thewood is satisfactorily fire-proofed. Wood so treated, can be shellacedor varnished according to ordinary practice with no difference in itsinitial or later appearance from similar wood which has been finishedwith a coating of shellac or varnish without having been first subjectedto a fire-proofing treatment.

In the preferred practice of my invention I employ a solution ofammonium phosphate containing about 40 parts by weight of the salt in100 parts by weight of water. Either ammonia gas or aqua ammonia isadded to the salt solution in an amount sufphere for a few days orotherwise drying it,

the ammonia volatilizes so that the surface of the wood is no longeralkaline and consequently any desired finish coating may be appliedthereto without being attacked by any of'the materials used in treatingthe article to fireroof it. It will be obvious that instead 0 employingammonia gas or aqua ammonia with the ammonium phosphate solution, theremay be added to such solution a material such as caustic soda which willreact with a part of the ammonium compound to liberate ammoniatherefrom. My broadly the employment with a fire-proofinventioncontemplatesing solution of any gaseous or volatile alka-,

line agent or any material or materials from which such alkaline agentwill be evolved or produced in use. I

Although I prefer to treat the article which has been made into thedesired form, in order to fire-proof it as described, it will be obviousthat if desired the untreated material from which the article is to beformed may, with some measure of success, be subjected to myfire-proofing treatment, and the furniture subsequently formed from thefire-proofed material.

If a piece of wood which has been treated in accordance with thehereinabove described process be subjected to a temperature sufficientto char or ignite it, either by inserting it into a furnace orotherwise, it has been found that upon removal from the source of heatthe flame lasts only for a few seconds, say for from 5 to 15 seconds,whereas if a similar piece of wood which has not been treated tofire-proof it is charred or ignited, upon withdrawal from the source ofheat the flame lasts for many minutes or until the wood is completelyburned up.

By the term furniture it is intended to include not only such articlesas desks, chairs, and the like, but also doors, door casings, windowcasings, partitions, wallboard, and other wood or like cellular buildingmaterial. If the finished article is to be subjected to the weather, thefire-proofing coating must be protected from the elements by a coatingof paint or varnishor other protective coating. Obviously it 1 would bedesirable to emiploy such a protective coating on wood oors in order toprotect the salt which has been depos1ted m the fibers ofthe wood frombeing washed out when the fioor is scrubbed.

The term volatile alkaline im regn'ation promoting agent as used hereinis intended to include any material having a basic character which uponaddition to a solution of a fire-proofing salt imparts temporarily abasic character thereto, whereby the soluthe first term amines, orfreely volatile as in the case of some of the higher amines.

The term non-metallic as employed in the claims is used in its ordinarysense as indicating the absence of metals such as zinc, copper and thelike, either in the form of the metals themselves or in the form ofcompounds of such metals. The term is not intended to indicate theabsence of elements commonly termed base-forming metals, such as thehypothetical alkali metal ammonium, or the like. Such elements areunderstood to be non-metallic.

Although I have described in detail the preferred practice of my processand the materials which I refer to employ, it is to be understood that Iam not limited thereto except as set forth in the subjoined l claims.

I claim:

1. The process of producing fire-proofed wood and like dense cellularproducts which comprises treating such products ,with a solution 10fammonium phosphate in the presence of free ammonia, such treatment beingconducted at substantially atmospheric pressure, and at a tem eraturenot materially in excess of prevailing atmospheric temperature, anddrying the treated products.

2. The process of producing fire-proofed wood and like dense cellularproducts which comprises treating such products witha solution ofammonium phosphate containing about 40 parts by weight of ammoniumphosphate in parts by weight of water 1n the presence 0 ammonia in anamount sufiicient to produce a solution having a pH value of about 8.5.

In testimony whereof I afiix my signature.

RALPH H. MOKEE.

